Before you get in over your head follow Bill's advice...

"When you turn the key ON, do you hear the carb solenoid click? Sometimes when stored, water in the gas can corrode the plunger in place. If it can't move, no fuel through the jet"

... and check that the carb solenoid is clicking and working properly. That will stop the fuel flow to the engine.

My John Deere L100 is 10 years old. It will run for about 15 minutes after cold start, but then starts stalling. The battery is new, the fuel filter was changed in the spring and I sevice it myself every year. Plug is about 1 year old. Took the fuel cap off and it started, ran for a about 15 minutes, and then started to stall again. Plenty of fuel in the tank. Any ideas for the root cause?

" Took the fuel cap off and it started, ran for a about 15 minutes, and then started to stall again. Plenty of fuel in the tank. Any ideas for the root cause?"

Did you repeat removing the cap to see if it would run another 15 minutes?
IF that cycle repeats, you likely have a clogged vent in the fuel cap.

HI i my john deer did same i found it sheared the key way under the magneto nut and timing was out 180 deg .just made new woodref key from alloy and away it went ..cheers

My john deerel108 choked with grass and died now it only spins over with back fireing everynow and then

Sounds like something valve related, a loose rocker perhaps? Could be a funky spark plug or flywheel key as well.

If all else fails, pop off front valve cover. Check push rods. One is steel, one is aluminum. Many times aluminum rod wears through and breaks in two, won't allow gas to cylinder. Easy fix for a $10 push rod. Put rag under when you take cover off, has oil in it.

Our new JD mower just did the same thing. It has about 10 hours on it. I used it for about 5 minutes and then turned it off. Went to start it about 4 min later and it won't start. I tries to turn over but won't

I have a John Deere g100 and it cranks fine but won't start. Changed the plugs. There is gas getting to the car. I removed air filter and tried and still nothing.

Will a burst of carb spray into the carb throat make it want to fire? Is the choke closing?

Just read all the above... I have a LA125, 10 yrs old. I was mowing in tall grass and engine bogged down, so I lifted the deck up and engine started running good. Made one more loop around yard, then the motor started dying (acted like it ran out of gas). I tried starting again and it ran about 20 seconds and died. I had just filled the tank to the brim (I have 3.5 acres to mow). So first thing I did was to R&R fuel filter. No luck. Checked spark plug (RC12YC), it's got spark. Let it sit overnight with battery charging. Cranked engine early AM in chocked setting; moved gas lever up and down; cranked engine at least 1 minute, but it's not firing. I'm going to try starting fluid in CARB next.

Anybody know if "Carburetor Cleaner" can be used for Starting Fluid?

Most can, yes. I like the Super Tech Walmart stuff. Some of the chlorinated cleaners don't work. Possibly water in the fuel? If it doesn't want to at least try to run, try a new spark plug before delving deeper. Other issues on this engine can lie under the valve cover, or sheared flywheel key etc.

Put in new plug *RC12YC", put a couple blasts of Starting Fluid in Carb venturi, cranked her over... and she started (momentarily). I listened very carefully when I turned on the Ignition and I did NOT hear any clicking... That leads me to think the Carb Solenoid is bad. So I ordered one off Amazon, along with a new gas cap, a new air filter cartridge, and a HIPA Fuel Pump. I'll update when parts get here.

Yep , filter. Fresh fuel. Check solenoid ...when you purchase your next carb cleaner or even starting fluid buy the best ! This will ensure other than solvency the product will also have lubricity which shall protect your engine internals while cleaning !

I took mine to JD for repair and it was the automatic choke They replaced the whole little something or another - they said the way it was machines. They have been having problems with that.

It's been raining here (NE Florida) so much, I hadn't been able to work on my John Deere. So yesterday, got the vacuum fuel pump replaced and the Carb's solenoid, a new air-filter, plus A new gas cap. I can now hear the 'click' from the Carb solenoid. So I squirted starting fluid in venturi and fired it up. It only ran for a few seconds... Next I squirted in 4 blasts, cranked motor, when it started firing, I hopped off seat and kept squirting starting fluid in venturi. I had it running about 2 minutes... but it wouldn't run on it's own. I noticed the brand new fuel filter didn't have hardly any gas in it! Weird! I would think it would have been full... I even retried with new gas cap removed... same thing!!! This is so frustrating... the grass out front is a jungle! I wish I could pressurize the gas tank to see if there is a clog in the fuel line... ( I had just filled the tank to the brim minutes before my JD LA125 conked out on me). Any suggestion here would sure be helpful. Cheers, me

Remove the fuel cap and blow back to the tank from behind the fuel filter. You could then put a few pounds of pressure by leaving the line off and holding your hand mostly over the cap is you wish. Your fuel filter should it fill won't stay that way for long. Most times they are 1/4 full at best. If the siphon is made, fuel will come out the line from the tank on its own. (They draw from the top of the tank through a straw. ) You could drop a length of fuel line into a gas can and attach it to the pump for an easy test as well.

Thanks Tomplum... I have lots of work to do today, but I'll have ALL day Saturday to work on this...

I haven't read the entire thread, but some have experienced problems if they did not use a JD fuel filter.

Yep heard that before with JD , Micron sizing is important for proper flow !

As Tomplum suggested, I removed the supply hose from the fuel filter and blew into the fuel line, I could hear bubbling from the tank... So I know the line isn't clogged. I bought a HIPA fuel pump and fuel filter from Amazon (https://www.amazon.com/dp/B079QGPMHG/ref=cfb_at_prodpg). I made sure the fuel filter wasn't backwards. I squirted starting fluid in the carb and cranked it over... it'll run a little bit... but I don't see any fuel in the filter. I shot starting fluid into the venturi about 8-10 different times, but it wouldn't keep running. What has me puzzled is the fuel filter didn't have an arrow (indicating flow direction). I went to my local Auto parts store and checked all their filters... I'm sure I have it installed correctly. I think I'll go back outside and just bypass the fuel filter and see what happens. Anybody concur with this? I appreciate your help. I don't have $ to buy a new lawn tractor, my Bahia grass is about 30" tall.

Jeff , yes for short term testing always bypass a potential blockage to flow . Don,t forget Tom,s advice to simply draw fuel from elevated gas can to the fuel pump for testing also !

UPDATE: This morning, I verified the gas is free flowing from the tank, to the fuel filter, to the vacuum fuel pump, and up to the carb. I tried cranking the motor after squirting starting fluid in venturi till the battery started getting weak. It would run till it burnt off the starting fluid... but never would run on it's own... So it must be the carb that has the problem... I ordered a Rebuilt carb off Amazon, and it will be here Aug 9th... I pray the new carburetor will solve this! Amen (I will keep this updated)

Here's an excellent video on R & R a carburetor on a Briggs & Stanton 21HP motor. Just in time for my new carburetor I received today!

https://youtu.be/ij_VRC-57JU

Don,t throw out the old carb . Just dismantle and let it soak in concentrated carb cleaner. Clean it up for a spare . Lots of video,s on cleaning on the same site that provided the r&r info , you will need it .

I watched that video above, and heard mention of a Governor Spring on the Carburetor... that made me think of the broken spring I found on my mower deck when I first started debugging this problem. Looking further into this Governor Spring, I came across this video: https://www.youtube.com/watch?v=npde5DOt6hA. (I left a comprehensive comment there) Now I'm wondering if this was my problem from the get-go. Either way, I have to get down to removing the control bracket and see if the spring is missing. The beat goes on...

Well lol I guess you will find out when you install the Rebuilt carb . If it,s the bigger main gov spring no . The idle spring will effect starting . Let us know how it goes Jeff !

I've been super busy, so I wasn't online for several days. ( I verified
the Governor spring was in-place). I successfully R & R'd the carb,
and got the engine to run... but only in the full-choke position and down to about 1/2 way. I tweaked the carburetor adjustments, but failed to keep engine running when the throttle was just below the 1/2 way point. I had Ag-Pro come and pick it up, they can fine tune it. I just gave up fighting this nemesis for the last 4 weeks... I sure learned a lot and thank all you guys that helped me with this... I pray I don't have to come back next week ssewalk1... LOL.... Cheers! ;-)

No Problem Jeff ! Let us know what they diagnosis Bud , All The Best !

If you are sure spark is present, give it a shot of starting fluid in the carburetor. If it does not start check for compression. Still no start make sure timing is good and valves are operating properly.

An engine needs fuel, air, compression, and spark to run so check things out one at a time and I am sure you will get it running

How do I close my post? I finally bought another lawn tractor... I looked on this page, but cannot find how to close... Thanks for your help

You just did Jeff ! I suppose the diagnosis was terminal ?

Yeah, it was a blown head gasket... The Ag-Pro Repair guy said it wouldn't be worth anything as a trade in... and repairing would be kinda cost prohibitive... Mowing season is coming to an end soon, so I'll put it on Craig's List or MarketPlace... I have a bundle of new parts on it, so I'll put 'er up for sale around late March early April. Thank you for sticking by my side... Blessings, Jeffrey

Jeff , with what you have invested into this , I would invest another few dollars and replace the head gasket and check the valves an rockers , when time and $$ permits . This really is a diy type job .You most definitely had marginal compression which was the basic cause . Worst case scenario you will get much more from a running unit than parting it out . Best scenario you will have a 2 nd tractor for cart hauling or back up usage !

Ag-Pro Repair guy is obviously a good salesman.

Unfortunately Yes , apparently Wheely !

We'll see how things go (financially), I might try the DIY fix ssewalk1... I had 10 good years on the JD... This is a pretty cool site... I've enjoyed all you guys help & advice. Cheers! ;-)

Yep some pretty cool Gearheads , Welcome aboard don,t be a stranger and good luck Bud !

I have a JD L130. It will cranks over real good until the battery goes down. I am getting gas to the carb and the gas is fresh in it. The gas and air filter is good also spark plugs. I can spray starter fluid and it will start and white smoke will come out and then it will die. As long as I spray fluid in it, it will run. I am getting gas all the way to the carb. Please help I cannot afford and new one right now, we have medical problems in the family now and that comes first Thanks.

Read this entire thread , it's self explanatory . Then ask us pertinent questions , no need to reinvent the wheel when the answers have already been given !

A couple of things to check. The excessive smoke and the engines inability to run off the fuel in the carb can be from adding diesel fuel rather than unleaded fuel. Best give a quick sniff to the supply can used. Water present in the carb or the solenoid not opening at the base of the carb could also be the gremlins you seek. Best of luck with all going on.

Thanks for your reply. Unlike the other comment,yours was right. I put gas in it twice thinking it was good gas but was mixed. My cans were switched. After putting good gas in it and spraying starter fluid till the old gas got out and stop smoking, it started running good. I have no reason to have diesel fuel around. Thanks again and hopefully things will be better with God‘s help and grace.

All The other answers previously we're correct within common sense and causal specific . Running old mixed gas in a straight gas application is almost as idiotic as filling it with diesel . Don,t rely on God's intervention , in the future label your fuel cans lmao .

Thanks for your comment. I will keep that in mind and for your information, I did not ask for God’s Intervention on this. You have a nice day.

Glad that you had a simple fix. Best to you and yours. Tom

Corvette glad to hear you have no reason to have diesel fuel around , God Bless !

I had the exact same issue...replaced fuel pump, spark plug, cleaned fuel lines and replaced fuel still no start. Turns out the intake valve push rod (aluminum) was bent... replaced it and re-gapped the valve rocker arms and the engine started immediately!

Anyone know why B&S used aluminum valve push rod?

Answer: IT ALWAYS BENDS! Very poor design I think. I've never seen that in a car or ANY other mower I've owned in the last 50 years.

"Anyone know why B&S used aluminum valve push rod?"

They couldn't figure out how to wire up a warning light for when the valve guide tries to leave the head....

My battery was dead on my L100 so I charged it over night. Now it cranks well but will not start. Also, I cannot hear a click when I turn the ignition key on. I suspect the charging messed something up! Any thoughts?